1. Field of the Invention
The present disclosure relates to a liquid crystal display apparatus, and more particularly, to a liquid crystal display apparatus capable of improving uniformity in luminance of RGB pixels by asymmetrically designing RGB pixels, and enhancing display quality.
2. Discussion of the Related Art
Liquid crystal display apparatus (hereinafter, referred to as ‘LCD apparatus’) have been widely used owing to development of mass production technology, easiness of driving means, low power consumption, high resolution, and large-sized screen, and furthermore, its application field has been gradually expanded.
FIG. 1 illustrates a pixel structure of an LCD apparatus according to the related art.
Referring to FIG. 1, a plurality of gate lines 10 and data lines 20 are provided in such a manner that the gate line 10 crosses the data line 20, to thereby define a plurality of pixels 30.
The plurality of pixels 30 may include red, green, and blue pixels. One red pixel, one green pixel, and one blue pixel being adjacent each other in a direction constitute one unit pixel.
A data voltage supplied to the pixel 30 is switched through a switching element 40, wherein the data voltage controls transmittance of light emitted from a backlight unit, to thereby display color images. In this case, the switching element 40 is formed of a thin film transistor (TFT).
The LCD apparatus according to the related art is provided in such a manner that the red, green, and blue pixels are designed symmetrically. That is, all pixels have the same length (x) and width (Y). Also, the switching element 40 is identically positioned in the respective red, green, and blue pixels.
A display quality of the LCD apparatus may be determined according to various factors, wherein one of the most important factors is luminance of image. In this case, the luminance of image may vary according to brightness of backlight, luminance properties of color, and light transmittance of pixel including liquid crystal, wherein the light transmittance of pixel is aperture ratio of pixel.
If the brightness of backlight is predetermined and as shown in FIG. 1, all the pixels 30 have the same aperture ratio, the luminance of image may vary mostly according to luminance properties of color. The luminance of white color may vary according to the color properties of the red, green, and blue pixels, wherein the color properties of the red, green, and blue pixels include color coordinates and luminance of the red, green, and blue pixels.
In this case, white colors with different color coordinates are obtained by the color coordinates and luminance combination of the red, green, and blue pixels.
Manufacturers of the LCD apparatus may have the same requirements for the red, green and blue colors, however, may have the different requirements for the white color. For example, some manufacturers require that a color coordinate of white color (X,Y) should be (0.318, 0.318), while other manufacturers require that a color coordinate of white color (X, Y) should be (0.310, 0.320). As mentioned above, a white color in a color coordinate such as (0.310, 0.320) can be obtained by the color coordinates and a luminance combination of the red, green, and blue pixels.
On the luminance properties for each color, the green color is at the high level; the red color is at the intermediate level; and the blue color is at the low level. Supposing that all the pixels have the same aperture ratio, generally. In this case, if the luminance of green pixel is 100%, the luminance of red pixel is 90%, and the luminance of blue pixel is 78%, generally.
Thus, if all of the red, green and blue pixels have the same aperture ratio, a distortion in the color coordinates of the white color may occur due to the different luminance properties of the respective colors under the circumstances that the color coordinates of the red, green, and blue pixels are maintained.
In order to adjust the color coordinates of white color under the circumstances that the color coordinates of the red, green, and blue pixels are maintained, it is necessary to adjust the luminance ratio of the respective red, green and blue pixels.
A method for adjusting the luminance in the red, green, and blue pixels may be carried out by adjusting a gamma value or adjusting light transmittance of the pixels (i.e., aperture ratio of the pixels).
FIG. 2 illustrates a pixel design changed to decrease luminance deviation by each color.
Referring to FIG. 2, the related art LCD apparatus is provided in such a manner that the aperture ratios of the red pixel, green pixel, and blue pixel are adjusted to decrease the luminance deviation by each color.
For example, if the aperture ratio of the blue pixel whose luminance is at the low level is 100%, the aperture ratio of the red pixel may be decreased to 90%, and the aperture ratio of the green pixel may be decreased to 78%. Thus, the luminance deviation by each color may be decreased by adjusting the aperture ratio of the pixels, thereby the color coordinates of white color may be adjusted.
In this case, luminance values of the red pixel, green pixel, and blue pixels are set to the maximum values. Thus, if adjusting the color coordinates of white color by adjusting the aperture ratios of the red pixel, green pixel, and blue pixel, the loss of entire transmittance may occur in a panel, thereby lowering the luminance of image and degrading the display quality.